Anti-arrhythmic drugs (also referred to as “anti-arrhythmic agents” or “antiarrhythmic drugs”) are a group of pharmaceuticals that may be used to suppress abnormal heart rhythms (also referred to as “cardiac arrhythmias”). Examples of types of cardiac arrhythmias may include ventricular or supraventricular arrhythmias, such as non-sustained ventricular tachycardia, sustained ventricular tachycardia, ventricular fibrillation, premature ventricular contractions, long Q-T syndrome, atrial fibrillation, atrial flutter, and premature atrial contractions.
Anti-arrhythmic drugs may be classified, such as based on exerting inhibitory activity on different phases of the cardiac action potential. Anti-arrhythmic drugs may include Class III anti-arrhythmic drugs (also referred to as “Type III”). The mechanism of action of Class III anti-arrhythmic drugs may include inhibiting potassium channel outflow, which may increase the refractory period of the cardiac action potential.
An electrocardiogram (EKG or ECG) represents an intrinsic electrical cardiac signal, which includes atrial and ventricular depolarizations. Class III anti-arrhythmic drugs may prolong the Q-T interval of the EKG. Class ill anti-arrhythmic drugs may have other effects, such as slowing heart rate, slowing atrioventricular nodal conduction, and prolonging refractoriness. Examples of Class III anti-arrhythmic drugs may include amiodarone and dofetilide. Amiodarone may have other effects, and thus may be included in Classes I, II, and IV. Because amiodarone may prolong the Q-T interval, it may be considered pro-arrhythmic.
Patients with cardiac arrhythmias may be treated using anti-arrhythmic drugs, medical devices, other therapies, or any combination thereof. Medical devices may be ambulatory or non-ambulatory. Ambulatory medical devices (AMDs) may be used to monitor and/or treat patients with cardiac conditions. Examples of AMDs may include subcutaneous and other implantable medical devices (IMDs), wearable medical devices and other external medical devices. IMDs may include pacemakers (also referred to as “implantable pulse generators” (IPGs) or “artificial pacemakers”).